Cleanliness is down to your design, layout and application. When it's not clean enough, your PIC will soon-enough complain by restarting or by some other delinquent behaviour.

There is no rule that says 100uF and 100nF is the cure for all ills. Most of my designs have only 10uF following the Regulator but augmented with a liberal sprinkling of 100nF's in places where in my judgement they'll do the best good.